Fire control or like apparatus for similar purposes



J ne 17, 1947- M. K. INGOLDBY ET AL FIRE CONTROL OR LIKE APPARATUS FOR SIMILAR PURPOSES File'd March 19, 1942 '5 Sheets-Sheet 1 June 17, 1947. v M. K. INGOLDBY ETAL FIRE CONTROL OR LIKE APPARATUS FOR SIMILAR PURPOSES Filed March 19, 1942 5 Sheets-Sheet 2 June 17, 1947.

M. K. INGOLDBVY ET AL FIRE CONTROL 0R LIKE APPARATUS FOR SIMILAR PURPOSES Filed March 19 1942 5 Sheets-Sheet 3 m M 'Jw Patented June 17, 1947 FIRE CONTROL R LIKE APPARATUS FOR SIMILAR PURPOSES Maurice Kerr Ingoldby, deceased, late of Tynemouth, England, by Thomas Frederick Clarke, Swanley, England, and Percy William Cole, Purley, England, executors, and Johann Hermann Abbink-Spaink, Jesmond, Newcastle-on- Tyne 2, England, assignors to Vickers-Armstrongs Limited, London, England, a British company Application March 19, 1942, Serial No. 435,355 In Great Britain April 21, 1938 8 Claims. 1

This invention relates to gun-fire control or like apparatus for similar purposes and is concerned particularly with the transmission of measured displacements to a gun whereby the latter is adjusted automatically upon its mounting. It will be clear from the following that the invention is not limited in its use to the transmission of displacements in the fire control of guns and the apparatus might well be employed for the control of searchlights or other displaceable objects.

It is the primary object of the invention to provide apparatus which will operate from a very small controlling torque such, for example, as the torque developed in the mechanism of an indicating instrument.

In accordance with the invention in gun-fire control or like apparatus there is provided apparatus for the transmission and power amplication of measured displacements from a director to an object being controlled thereby, wherein the director is arranged to control a photoelectric device in such manner that when the director is moved in one direction it allows a photo-electric element of said device to be exposed to exciting radiation whilst when the director is turned in the other direction it allows a further different photo-electric element to be exposed to exciting radiation, said photo-electric device being associated with an electric follow-up motor, the direction of operation of which is controlled according to whether the one or the other of the photo-electric elements is energised and the follow-up motor operating always in such manner as to tend to restore the photo-electric device to a state of rest whereby the electric motor follows up the movements of the director, and wherein the follow-up motor has its output applied to the control of a hydraulic pump and motor unit, the power output of which is employed for impartin the controlling movements to the controlled object. The hydraulic pump and motor unit may be of any suitable type and may be provided with suitable hunter valve gear for its control.

In order that the said invention may be clearly understood and readily carried into effect, the same will now be more fully described with ref erence to the accompanying drawings, in which:

Figure 1 shows diagrammatically the lay-out of an apparatus built in accordance with the invention:

Figure 2 shows also partly diagrammatically a constructional form suitable for carrying the lay-out of Figure 1 into p a and 15 movements of the gun mounting.

sponding receivers I3, I4, I and I6.

2 Figure 3 is an electrical diagram of an electric power amplification unit employed in the construction shown in Figure 2.

For the sake of generality, in Figure 1 there is 5 indicated a training handwheel I and an elevating handwheel 2, the movements of both handwheels representing the movement that it is desired to impart to a gun mounting by means of correspondin power shafts 3 and 4. It is required that the shafts 3 and 4 have movements representing those of their corresponding handwheels I and 2 but that such movements of the shafts 3 and 4 should be powerful so as to ac complish the actual elevating and training The handwheel I drives through gearing to a shaft 3A which extends to a transmitter 4A. There is gearing 5 between the shaft 3A and a further shaft Ii driving a transmitter I. The gearing 5 is such that the shaft 6 makes a plurality of revolutions for each revolution of the shaft'3A. The transmitter I, therefore, is regarded as a fine transmitter and the transmitter 4A is regarded as a "coarse transmitter. The handwheel 2, in like manner to the handwheel I, drives onto a shaft Figure 2, the photo-electric devices I1 and I8 controlling a follow-up motor 2|, and the photoelectric devices I9 and 20 controlling a follow-up motor 22. The motor 2I operates a hydraulic pump and motor unit 23 whilst the motor 22 controls a similar unit 24. The output shafts of the units 23 and 24 are formed by the shafts 3 and 4 previously referred to.

It will be seen that the photo-e1ectric device I8 is carried upon a shaft 25 having a geared connection 26 with a shaft 21 associated with the photo-electric device IT. The gear ratio of the gearing 26 is the same as that of the gearing 9 so that if the photo-electric devices I1 and I8 cause the shafts 21 and 25 to run following the movements of the receivers I3 and It, then the gearing 25 will operate and the shaft 3, through its gearing 28, may run smoothly in correct relation with the shaft 21. In like manner, the shafts 29 and 30 respectively associated with the photoelectric devices I9 and 20 are connected by gearing 3| having the same gear ratio as that of the gearing 5, so thatunder normal conditions of operation the output shaft 4 connected by gearing 32 with the shaft 38 may run in correct relation to the latter. As will be explained here inafter, should the fine transmissions having the photo-electric devices I! and 28 become, for some reason, disturbed in their synchronism, then the coarse transmissions are arranged to apply the necessary corrections in order to restore the coincidence of the fine transmissions through the gearing 28 and 3|.

Referring now to Figure 2, there is here shown a telescope 33 which may be regarded as equivalent to, say, the handwheel i of Figure 1. The telescope 33 is carried upon a shaft 34 which supports a gearwheel 35 meshing with a further gearwheel 36 which, in turn, engages with a pinion 31 on a shaft 38 of a transmitter unit 39. The latter may be of an electrical type and there is a similar transmitter unit 48 mounted upon the shaft 34. The gearing 35, 36 and 3! is such that the shaft 38 will make a plurality of revolutions for one revolution of the shaft 34. The transmitter 40 is,: therefore, regarded as the "coarse transmitter and the transmitter 38 as the fine transmitter. There are connections illustrated diagrammatically at 4! and 42 from the transmitters 40 andj39 respectively to receivers 43 and 44. The receiver 43 is the coarse receiver whilst the receiver 44 is the fine receiver. Each receiver is associated with a corresponding photo-electric device 45 and 46, and it will suffice here to describe only one of these devices since they are precisely similar. The receiver 44 has a shaft 4! to which there is attached a semi-circular screen 48 of opaque material. A frame 48 is supported upon a shaft 58, the latter being co-axial with the shaft 47 of the receiver 44. The frame 49 serves to support a pair of lamps which are located to one side of the screen 48. Upon the other side of the screen 48 the frame supports photo-electric cells 52, suitable optical lens systems 53 being located between the lamps 5i and their respective photo-electric cells 52 so as to concentrate a beam of light from each source of light onto the corresponding photo-electric cell. The shaft 58 carries a slipring member 54 with cooperating brushes 55. Connections are made from the individual sliprings, conveniently through the shaft 58 which may be hollow, so that electric currents may be constantly supplied to the lamps 5 I and also so that the output from the photoelectric cells 52 may be taken from the appropriate siiprings. The electric connections from the brushes 55 are indicated at 56 and are seen to lead to an amplifier 51. From the latter, an electric motor 58 is supplied with field and armature currents through connections indicated at 74. The arrangement of the amplifier is such that if one of the photo-electric cells 52 is energised, this causes an amplified current to flow in the armature of the motor 58 in a particular direction whereas if the other of the photoelectric cells 52 is energised, an armature current in the opposite direction is introduced in the motor 58. An energisation of one of the two photo-electric cells is brought about when the screen 48 is moved angularly. In a normal position of the apparatus, the screen 48 shields both photoelectric cells so that when the lamps 5! are in operation no light from the lamps 5| may fall upon the sensitive part of said photo-electric cells. An angular movement of the screen 48 progressively uncovers one of the cells so that progressively an increasing current flows in the stant field excitation of the motor 58 the latter would run in the one direction or the other depending upon the direction in which the screen 48 hasbeen moved and with a torque depending only on the armature current. Such a system might not be both accurate and sensitive in regard to following up the movements of the screen 48 when the screen is rapidly accelerated or decelerated. To overcome this difliculty, the shaft 41 of the receiver 44 carries a disc 59 which is radially slotted as at 58. Upon one side of the slotted disc 58 there is supported a photo-electric cell 8i and upon the other side a. lamp 62 together with a suitable optical lens system 83 for concentrating the light from the lamp and focussing it onto the photo-electric cell 6!. It will be understood that when the lamp B2 is in opera tion, the frequency with which light will fail upon the cell 6| will depend upon the speed of rotation of the disc 59. There are electric connections 84 from the photo-electric cell SI and to the lamp 82 to supply the latter with electrical energy, and to connect the photo-electric cell to the amplifier 51. The connections 54 enter the electric amplifier unit 51. The latter is arranged so that the field current which it supplies to the motor 58 is proportional to the frequency of energisation of the photo-electric cell 8i which frequency is, of course, in turn proportional to the speed of the receiver 44.

The receiver 43 has a shaft 55 associated with the screen 88 of the photo-electric device 45. The latter has a shaft 51 and a slipring member 68 associated with brushes 59 which are joined by a connection H! to' the electric amplifier unit 51.

It will now be understood that if the telescope 33 is angularly adjusted, then for one revolution of the shaft 34 the shaft 38 will make a plurality of revolutions and similarly the fine transmitter 38 will experience a plurality of revolutions which it will communicate via the connection 42 to the fine receiver 44. The latter will cause corresponding displacement of the shaft 41 which will move the screen 48 relative to the photo-electric cells 52 so that one of the latter is exposed to the light'from its respective light source 5|. The current in the armature of the motor 58 will develop in a corresponding direction so that the motor tends to run and thereby shifts the frame 48 in such manner as to bring that photo-electric cell 52 which is exposed to light radiation back to a position where it is behind the screen 48 and where it is no longer subject to such radiation. In a manner previously explained, the field current in the motor 58 will depend upon the speed of operation of the receiver 44. Any rotation of the shaft '58 will be communicated to the gearwheel 1| mounted thereon, such gearwheel meshing with a further gearwheel 12 which, in turn, meshes with the gearwheel 13 mounted upon the shaft 81. The ratio as between the gearwheels II and 12 and 13 is the same as between the gearwheels 31, 38 and 35. The receiver 43 operates in like manner to the receiver 44 except, of course, that it has the different gear ratio drive at the transmitter end. Whilst both receivers are running in coincidence and whilst the follow-up motor 58 is in coincidence with the receiver 44, the coarse receiver 43 does no useful work. If, however the fine receiver 44 and the follow-up motor 58 should tend to get out of step, the coarse receiver 43 and its associated photoelectric device 45 takes control and resets the fine stage since the screen 86 will expose one of the photo-electric cells of the device 45. When the coarse stage of the apparatus achieves its resetting action the fine stage will continue to operate correctly within its limits of accuracy. This desired operation is secured with the aid of the electric amplifier unit which has an output connection indicated at I4, supplying the field and armature currents to the motor 58.

The motor 58 has an output shaft I5 which enters a hydraulic pump and motor unit I6. The shaft I5 controls a valve in the unit I6, the valve being associated with a hunting gear so that the off-set of the valve from a zero position causes a power output shaft 11 of the unit to operate and, incidentally, to tend to restore the valve to a zero setting. With a hydraulic pump and motor unit as described, there will be a certain amount of lag in the hydraulic system due to the hunting gear. To overcome the difficulties due to lag in this particular instance, the shaft 15 is geared to a shaft I8 which is, in turn, geared to a shaft I9 carrying one member 80 of a differential gear 8|.

The power output shaft 11 is in like manner geared to a shaft 82 which is also geared to one side of the differential gear M. The member 83 carrying the planet wheels of the differential gear is connected with a gearwheel 84 meshing with a further gearwheel 85 carried upon a shaft 86. The latter communicates its mechanical drive to a shaft 81 to which there is secured a worm 88 meshing with a worm ring 89 secured to the outer casing of the fine receiver 44. with the arrangement of the differential gear BI as described, it will be seen that one side of the differential gear receives a movement corresponding to the power output 11, whereas the other side of the differential gear receives a movement corresponding to that of the input shaft I5. Any difference between the movements of the shaft I5 and II will be shown by a movement of the member 83 of the differential gear. Any movement of such member 83 of the differential gear will be communicated by the shafts 86 and 81 plifier unit I8 so as to damp the movement of the shaft I5.

In Figure 3 of the drawings, an electrical circuit is shown corresponding to the electric power amplifier unit 51. X

The photo-electric cells 52 are indicated at 9| and the photo-electric cells associated with the photo-electric device of the coarse receiver 43 are indicated at 92, All the photo-electric cells 9| and 92 are disposed across a pair of common leads 93 and 94, which it will be observed are supplied from a rectifying unit consisting of the transformer 95 and rectifying valve 96, together with suitable smoothing condensers 91 and a choke 98. Feeding resistances are included in the parallel connections to each photo-electric cell. The photo-electric cells SI each have connections 99 and I00 with the grids IOI and I02 of thermionic valves I03 and I04. Transformers I05 and I06 are associated with each connection 99 and I00 and there are also means for introducing D. C.

grid bias upon the grids IN and I02 indicated by grid batteries I01 and I 08 which may, of course, be replaced by equivalent supply systems not involving the use of batteries. The transformers I05 and I06 introduce upon the grids of their respective valves alternating potentials which, in conjunction with the bias supplies I 01 and I08, determine when the valves concerned shall become effective depending, of course, upon the amount of light falling upon the photo-electric elements 9|. A supply transformer I09 is arranged with a tapped secondary and supplies the plate current to the valves I03 and I04 in such manner that the alternating plate potentials of the two valves are 180 out of phase. The plate supply lead of each valve includes a transformer I I 0 and III, the secondaries of which are connected to a further pair of valves H2 and H3. The secondary of the transformer I I I is connected by leads H4 to the valve 2 one to the grid and one to the cathode thereof. The secondary of the transformer I I0 is connected to the valve I I 3, by leads I I5 in like manner, but it will be observed that the valves II2 and II 3 are in reverse positions so that the output connections IIB therefrom will carry current either in one direction if, say, the one valve H2 is operating or in the other direction when the other valve H3 is operating. The output II 6 is connected with the armature of the motor 58 whereby the armature current thereof is determined according to the energisation of the photo-electric cells 9|.

From the description above, it will be seen that if one photo-electric cell Si is energised by a beam of light falling upon it, then the corresponding valve I03, for example, takes control and the impulse thereof will be communicated by the transformer Illl to the grid of the valve II3, whereupon the latter will supply output current upon the output connections I I6 and therefore to the armature of the motor 58. If the other photo-electric cell 9| is energised, an opposite current will be supplied to the armature of the motor 58.

Each of the photo-electric cells 92 has a, connection III to the control grid of an associated pentode valve II8 In the plate circuit of each valve there is arranged a relay winding II9 each of which is adapted to co-operate with a relay switch I20. Thus, should light fall upon either of the photo-electric cells 92, then the associated pentode valve I I 8 will operate and the relay winding II9 will cause its associated relay switch I20 to be opened. This causes opening of the corresponding grid connection of one of the valves I I2 and I I3 so that the particular valve in question is fully operative and maintains a maximum output until its grid circuit is once more closed. Thus, irrespective of the action of the photo-electric cells 9|, should a cell 92 of the coarse control he in operation then such coarse control photo-electric cells will over-ride the effect of the fine control cells and will produce maximum operating current in the armature of the motor 58.

The field of the motor 58 is formed by a winding I2I located in the output circuit I22 of a thermionic valve I23. The latter is of the same type as the valves H2 and H3 and has a control grid I24 which is connected to a transformer I25 and relay switches I20. The relay switches are opened when the relay windings I I9 are energised so that the grid circuit of the valve I23 is opened and it is fully operative to produce maximum cur rent through the field winding I2 I associated with the motor 58.

The photo-electric cell BI is eifectively connected to the grid of a pentode valve I21 which is choke capacity coupled to a power triode valve I28, the output of which is fed through a transformer I29 to a full-wave rectifying valve I30. In the output from the valve I30 there are smoothing elements consisting of a choke I3I and condensers I32. A loading resistance I33 is connected across the smoothed D. C. output from the rectifying valve I30, and across this loading resistance I33 the grid and cathode of the valve I23 are connected.

When the apparatus is in operation, the photoelectric cell GI will periodically receive light, so that electrical impulses of a corresponding frequency will be produced thereby. The characteristic of the valve system associated with the photoelectric cell BI is such as to give an amplification proportional to the frequency of the impulses from the photo-electric cell 6 I. Thus, the D. C. potential across the loading resistance I33 is proportional to the frequency of the light impulses falling on the photo-electric cell GI. Therefore, assuming that the relay switches I 26 are both closed, the plate current of the valve I23 will be proportional to the frequency of the light impulses falling upon the photo-electric cell 6! which frequency is proportional to the speed of operation of the fine receiver.

It will be apparent from the foregoing that the relay switches I20 and I26 are normally closed, but are adapted to be opened by the coils I I9. As long as these switches are closed, the grids of the valves H2 and II 3 are controlled by valves I83 and I 04, and in turn by the cells 9| of Figure 3, which correspond to the cells 52 of Figure 2.

The supply circuit to the motor 58 comprises the lead H6 and one or the other of the valves H2 or II3. This circuit is always completed, but the amount of current passing through the armature is controlled by the grids of valves H2 or H3.

Similarly, the field supply is taken from the lead I16 through lead I22 and valve I23 and is always completed, but the amount of current is controlled by the grid of the valve I23 according to the potential across the resistance I33, which in turn depends on the cell BI. In view of valves I21 and I28, transformer I29, and rectifier I30, this control'potential is a non-pulsating D. C. potential which is proportional to the frequency of pulsations produced by the cell 6 I.

The above conditions exist for the fine control. Now it is clear that the fine and coarse receivers 4-1 and 43 and their screens 48 and 66 rotate simultaneously but at diiferent rates. The screen 48 rotates faster than the screen 66 and consequently uncovers one of the cells 52 (M in Fig. 3) before the screen 56 uncovers one of the cells of the photo-electric device 45 (92 in Fig. 3). Under such conditions the fine control only is effective, the coarse control being inoperative. The fine control starts the operation of the hydraulic motor with the result that the active cell 52 (9 I) and the inactive cell (92) follow their respective screens. It should be clear that if the telescope 33 is moved slowly, the lag of the cells behind their screen will be small and the coarse control may never come into operation, even though the fine control screen 48 makes one or any number of complete revolutions.

On the other hand, if the telescope 33 is moved rapidly through a large angle, the fine control will first come into operation, but the screen 65 of the coarse control will advance far enough trolled by their grids.

relative to the associated photo-electric cells to uncover one of them. When that happens, one or other of the coils II 9 is energized through operation of the associated cell 92 to cause one of the relay switches I20 in the grid circuit of valve H2 or II3 to be opened and one of the relay switches I26 in the grid circuit of the valve I23 to be opened.

The activation of cell 92 does not complete the motor circuit, this circuit remaining just as it was except that the valves are no longer con- The result is that these valves "fire fully, i. e. operate without grid control, and maximum current passes to the armature and field. The photo-electric units follow up their respective screens rapidly, and as soon as cell 92 is again screened, the switches I20 and I26 close and the fine control takes over as before.

The above does, of course, represent only one constructional form of the invention and others may be devised. It may be seen that the motor 58 may be controlled so that its armature current is dependent upon the speed of operation of the receiver, whilst its field is changed in direction according to the energization of the one or the other of the photo-electric units 52. It will also be appreciated that in a simpler form of the apparatus in accordance with the invention, the coarse system might be omitted. The lag correction achieved with the aid of the differential gear Bl may be obtained in other ways and other constructional variations may be made, for example, in the photo-electric device.

In the above, and in the appended claims, reference has been made to a "director." It will be understood that this term is intended to refer to any kind of controller or movement initiating member, whether manual or automatic.

What we claim and desire to secure by Letters Patent of the United States is:

1. In gun-fire control or like apparatus for the transmisison and power amplification of measured displacements from a director to an object being controlled thereby, electrical remote control means responsive to movements of said director including transmitting means operable by the director, receiving means electrically coupled to and movable in synchronism with said transmitting means, photo-electric means associated with said receiving means comprising photo-electric elements, shielding means common to said elements operable to expose one of said photo-electric elements to exciting radiation when moved in one direction and to expose another of said photo-electric elements when moved in the other direction, an electric follow-up motor associated with said photo-electric means and rotated in one direction or the other depending upon whether the one or the other of the photoelectric elements is energized, a connection between said photo-electric means and said followup motor to move the photo-electric means to shielded relationship, and a hydraulic pump and motor unit driven from said follow-up motor and drivably connected to the object being controlled.

2. Apparatus as claimed in claim 1, wherein the photo-electric means comprises a driven and a following member, one of such members carry ing a pair of photo-electric elements and the other carrying the shielding means, said exciting radiation comprising a source of light normally shielded by said shielding means, and means operatively connecting said follow-up motor to said following member.

3. In a gun-fire control or like apparatus for the transmission and power amplification of measured displacements from a director to an object being controlled thereby, a fine transmitter and a coarse transmitter operable by said director, said transmitters being so coupled that for one revolution of the "coarse transmitter the "fine transmitter makes several revolutions, a "fine receiver and a coarse receiver, means connecting the fine and coarse" transmitters to the fine and coarse receivers so that the "fine receiver rotates in unison with the fine transmitter and the coarse" receiver in unison with the coarse transmitter, a photoelectric device associated with each receiver, each of said photo-electric devices embodying two photo-electric elements and shielding means for said elements operable to expose one of the appropriate pair thereof to exciting radiation when moved in one direction and to expose the other element of the same pair when moved in .the other direction, an electric follow-up motor, connections between said photo-electric devices and said follow-up motor to move said devices to shielded relationship, said photo-electric devices being coupled with the follow-up motor with the same velocity ratio as the coupling between the "fine" and "coarse transmitters, an electric amplifier connected to said photo-electric devices and including amplifying thermionic valve circuits to develop an output current in one direction when one of the photo-electric elements of one of said devices is excited and an output current in the other direction when the other photoelectric element of said device is excited, and connections for supplying the developed current from said amplifier to the follow-up motor.

4. In a gun-fire control or like apparatus for the transmission and power amplification of measured displacements from a director to an object being controlled thereby, a fine translnitter and a coarse transmitter operable by said director, said transmitters being so coupled that for one revolution of the coarse transmitter the fine" transmitter makes several revolutions, a. fine receiver and a coarse receiver, means connecting the fine" and "coarse transmitters to the "fine and coarse receivers so that the "fine receiver rotates in unison with the "fine transmitter and the coarse receiver in unison with the coarse transmitter, a photoelectric device associated with each receiver, each of said photo-electric devices embodying two photo-electric elements and shielding means for said elements operable to expose one of the appropriate pair thereof to exciting radiation when moved in one direction and to expose the other element of the same pair when moved in the other direction, an electric follow-up motor, connections between said photo-electric devices and said follow-up motor to move said devices to shielded relationship, said photo-electric devices being coupled with the follow-up motor with the same velocity ratio as the coupling between the fine and coarse" transmitters, an amplifier having its output circuit connected to said follow-up motor, means electrically connecting the photoelectric devices to the amplifier so constructed and arranged that when one of the photo-electric elements of one of thedevices is energized an amplified current flows in the armature of the motor in a particular direction and when the cooperating photo-electric elements of said device is energized the armature current flows in the opposite direction, a hydraulic pump and motor unit controlled by the follow-up motor and drivably connected to the object being controlled, and means to transmit to the fine receiver from the hydraulic pump and motor unit advancing movement corresponding to lag in the hydraulic pump and motor unit.

5. Apparatus as claimed in claim 1, including speed responsive device associated with the photo-electric means and operative to introduce a component of control into the follow-up motor dependent upon the rate of movement thereof.

6. Apparatus as claimed in claim 3, including a speed responsive device connected to the photo-electric device of the fine receiver comprising a source of light, a .photoeelectric cell, a slotted screen so disposed between said source of light and said photo-electric cell that the slots therein permit intermittent energization of said photo-electric cell with a frequency depending upon the speed of operation of the director, and means connecting said photo-electric cell through the amplifier to said follow-up motor to influence the torque thereof according to its frequency of excitation.

7. Apparatus as claimed in claim 4, wherein the means connecting the photo-electric devices to the amplifier comprise thermionic valve circuits including the photo-electric elements associated with the fine and coarse" receivers, and means to override the effect of the fine thermionic valve circuits when the photo-electric elements of the coarse receiver are excited.

8. Apparatus as claimed in claim 1, wherein the hydraulic pump and motor unit controlled by the follow-up motor comprises an input control shaft and a power output shaft and a diiferential gear mechanically connected at either side to said input and output shafts, said gear having a middle member which records any relative, displacement between the input and output sides of the hydraulic pump and motor unit and is connected to impart a corrective movement to said receiving means.

THOMAS FREDERICK CLARKE, PERCY WILLIAM COLE, Erecutors of the Estate of Maurice Kerr Ingoldby, Deceased.

JOHANN HERMANN ABBINK-SPAINK.

REFERENCES CITED The following referencesare of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,957,240 Young May 1, 1934 2,126,887 Hodgman et a1 Aug. 16, 1938 2,189,823 Vickers et al Feb. 13, 1940 2,191,792 Hill Feb. 27, 1940 

